The present invention relates primarily to so-called button-type electro-chemical generators.
Such generators commprise positive and negative electrodes enclosed between two collectors which form the generator terminals and which are fitted together and joined but insulated from each other as by means of an electrically insulative seal, thus forming a sealed casing. British Patent No. 561,820 describes such generators, which are in widespread use due to their small bulk.
The assembly of electrodes necessary separators and electrolyte are sometimes enclosed in sealed casings, generally of circular form, comprising metal shells, one of which serves as a metal base member and the other as a metal cover member, one of which shells is deeply engaged in the other. These shells are appropriately held together but are separated electrically by an insulative seal. Such generators must be made with great care. Faulty positioning of the seal between the two metal shells or too great or too small a compression in fitting the one shell into the other incurs the risk of deterioration or deformation of the seal, with consequent leakage of electrolyte and shortcircuits.
The present invention comprises a button-type electrochemical generator, comprising positive and negative electrodes enclosed between two collectors whose peripheral edges are spaced and which respectively form the negative and positive generator terminals and a moulded electrically insulative plastics frame forming with the collectors a sealed casing, portions of the frame overlying the peripheral portions of the collectors to hold the components of the generator together.
The insulative material of the frame may be allowed to penetrate during moulding into the space between the spaced-apart edges of the two collectors. To limit the depth of such penetation, however, it is advantageous to provide stop means in the form of an electrically insulative ring which encircles the assembly of collectors, electrodes and separators.
Alternatively, an elastomeric insulative seal member may be interposed between the peripheral edges of the two collectors, thus serving also as such stop means.
In a preferred embodiment, the two collectors are cup-shaped and with open ends which face inwardly so that the peripheral edges of the collectors lie between the planes of the outermost collector surfaces, the height of the frame being less than or equal to the distance between these planes. As a consequence, a group of such generators can be stacked to form a battery with the adjoining flat surfaces of adjoining collectors of opposite polarity providing direct electrical contact between adjacent generators.
Alternatively, where the frame extends beyond these planes, at least one of the collectors of each generator or both may be formed with central bosses to ensure electrical contact between adjacent generators when they are stacked into a battery.
To construct a battery with such generators, the metallic surfaces of the appropriate ones of the collectors of adjacent generators may be welded together. This welding is preferably carried out before assembling the component parts of each generator.
Objects and features of the invention are the provision of electrochemical generators and batteries of such generators whose structure insures effective sealing of the cells without risk of mislocation or damage of requisite insulative seal means between collectors of opposite polarity.
Other objects and features are simplicity of assembly with consequent reduction in manufacturing costs.